This is a canning vegetables guide for beginners, based largely on the NHCP canning guide, which contains techniques, safety measures and recommendations for proper preservation of your vegetables.
Home Canning Guide: Canning Processing Methods
Chiefly, there are 2 methods or techniques for home canning: pressure canning and bain marie. Normally, the bain marie is used for acidic foods, such as fruits or jellies.
Instead, for low acid foods (vegetables, meats, seafood), pressure canning is used because it destroys the spores of clostridium botulinum bacteria in food, thus preventing lethal food poisoning.
Can you reuse canning lids? Glass jars (e.g., mason jars) are the best option since you can reuse them several times and you only have to change the lids.
Make sure the jars do not have cracks or are in bad condition (rust, scratches, etc.). Jars, such as mayonnaise jars, are not recommended because they break with heat.
So, to use them:
- Clean: wash them with water and detergent.
- Sterilize: you can sterilize them with boiling water.
Whenever you are going to preserve vegetables, use new lids. It is important to follow the manufacturer’s instructions.
For example, metal lids should be heated before use. Also, examine them well to check for deformities, holes, etc.
Home Canning Guide: Vegetables for home canning
Examine vegetables meticulously to analyze their healthiness, condition, freshness, etc. If there is mold, stains, odors… throw them away. Then rinse them well.
For certain fruits or vegetables, it is recommended to blanch them (boiling water and then place them on ice).
Filling the jars
There are two techniques for vacuum sealing.
- Canning cold or raw: the vegetables are added to the jar and then that container is added to the pressure cooker.
- Hot packing: the vegetables are cooked, packed and added to the pressure cooker. This method eliminates the air in the tissues; therefore, the vacuum is increased. In fact, the time the food maintains its quality depends on the amount of air removed before sealing.
Important: the jars have to be in the boiling water until the moment of filling them with food.
Removing air bubbles
You can insert a plastic spatula or knife and slowly swirl the jar to remove air bubbles inside the jars. If necessary, you can add topping liquid.
Then, with a towel or cloth, wipe the rims and place the lid on. If you squeeze the lid excessively, it may deform and cause the jar to break under heat.
Important: this space is necessary for the expansion of the food as the jars are processed, and to form the vacuum in the cooled jars.
Home Canning Guide: Pressure canner
Check the stopcock, valves, pressure gauge before using the pressure canner. Remember to refer to the instructions for proper operation.
Filling the canner
- Fill the canner with hot water to 2-3 inches (5-7.5 cm). Then, place the jars on the rack to prevent them from tipping over and to allow a good flow of steam.
- Next, secure the lid of the canner and open the stopcock to ventilate for 10 minutes to allow the temperature to rise properly. Subsequently, the pot will pressurize in the next 3 – 5 minutes.
Time and Pressure
The time and pressure depend on the type of food, type of packaging, size of the jar and altitude of the location.
Correspondingly to altitude, as it increases, atmospheric pressure decreases, thus influencing boiling time.
For example, in places below 1000 ft (305 m) above sea level, boiling for 10 minutes is enough to eliminate bacteria and pathogens. But, in places with an altitude above 1000 ft meters above sea level, an additional 1 minute is needed.
Specifically, every additional 1000 ft meters of elevation, 1 minute is added.
In the link (Selecting, Preparing, and Canning Vegetables and Vegetable Products) you will find the recommended time and pressure for several vegetables.
Home Canning Guide: Processing
- Start the timing after having the correct pressure and time. Watch the pressure gauge for fluctuations in temperature. If there is an abrupt change, repeat the process.
- After finishing the process, wait 15-20 minutes for the pressure to reach 0. There are certain cookers that have timed cooling. If you have one of these, refer to the instructions.
- Next, open the stopcock, remove the lid facing away from you and remove the jars.
- If you see bubbling, this indicates that the vegetables are under vacuum and the lid is tightly sealed.
- Place the jars well separated on a rack or cloth and not on a cold surface.
- Let them rest for 24 hours. Afterwards, check that the lid seals properly. To do this, press the center of the lid with your finger. If the lid does not move or pop off, it is sealed.
- If a small amount of liquid is lost, do not open the jars to replace them. If they are sealed and the liquid is only slightly below the food, the food is safe.
- If a jar lost a lot of liquid or did not seal, replace the jar with a new lid, refrigerate for 2-3 days or reprocess within 24 hours.
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Storing Canned Foods
Label and store jars, unstacked, in a cool, dry place in the absence of light at a temperature between 50-69.8 F (10-21˚C). Food, after one year in storage, should be disposed of.
If jars are arranged in a place near the stove, sunlight, heat-generating appliances, the quality of the food decreases due to changes in temperature and humidity. For example, metal lids corrode and leakage occurs.
Home Canning Guide: Consumption
The proliferation of bacteria, as a result of poor processing, gives rise to gases, causing the caps to swell and consequently damaging the seal.
- Bad odors.
- Strange colors.
In such cases, it is considered as if botulinum toxin is present and handled as such:
Sealed jars: put them in a thick garbage bag and throw it in the container.
Incorrectly sealed jars (leaks, etc.):
- With thick rubber gloves, stir with the lids of the jar and place the jar in a saucepan.
- Add, carefully (without splashing), a minimum of 8-quart (7.5 L) of water. The water should cover at least 1 ich (2.5 cm) of the jar.
- Put the lid on and heat to boiling for 30 minutes.
- Allow to cool. Then drain the water and discard the food, lids in a thick garbage bag. The jars can be reused. Personally, I would not.
- Utensils and surface should be disinfected with household bleach. Specifically, 1-part unscented liquid household chlorine bleach (5 to 6% sodium hypochlorite) to 5 parts clean water. Let stand for 30 minutes and rinse.
- Throw away all used materials: gloves, sponge, cloth, etc. used.
- Certain tomatoes have pH values higher than 4.6, therefore, if they are to be canned as acidic foods, they must be acidified to a pH of 4.6 or lower with lemon juice or citric acid.
- Food canning is not merely a recreational or traditional activity because safety is paramount, therefore, you must use the approved recipes according to the vegetables.
- Dry Canning vegetables is not safe because without the added liquid, C. botulinum spores are not likely to be destroyed.